“Because I’m not sure," Trump added. "I mean, let people make their own determination.”

Stephanopoulos pressed Trump about not being sure about Rubio's eligibility.

“I don't know, I've never looked at it, George," Trump replied. "Honestly, I've never looked at it. Somebody said he’s not, and I retweeted it. I have 14 million people between Twitter and Facebook and Instagram, and I retweet things and we start dialog and it’s very interesting.”

Rubio responded to Trump's comments on "This Week":

Look, this is a pattern, this is a game he plays. He says something that’s edgy and outrageous, and then the media flocks and covers that and then no one else can get any coverage on anything else.

And that worked when there were 15 people running for president, it's not going to work anymore. I’m gonna spend zero time on his interpretation of the Constitution with regards to eligibility and I’m gonna spend all my time talking about what this campaign should be about.